The present invention relates to a construction for mounting a pump on a small watercraft of the water jet propulsion type.
A prior art watercraft of this type is exemplified in FIG. 1 of U.S. Pat. No. 4,541,808, and includes a pump duct 6 connected to the wall of a recess 3 in the hull, the connection being exposed to the air in the recess 3 around the duct. If the connection does not form a good liquid-tight seal, when the watercraft is gliding on the water and has a shallow draft, air may be sucked through the connection and into the pump and cause the impeller 4 to idle. This, of course, lowers the pump performance.
The connection may be sealed with a flowable fluid packing, which solidifies in a predetermined time but still remains elastic. However, such packing is sticky and therefore makes the assembly of the parts difficult. It takes skill to apply the fluid packing with a predetermined and uniform thickness to the connecting surfaces. Also, it takes time and requires an additional process step to apply a fluid packing when the pump is assembled, and to replace the packing when the pump is overhauled.
FIG. 6 of the accompanying drawings shows other prior art constructions, wherein, instead of fluid packing, a rubber seal member S is interposed on the front end E of the pump casing, which is the connecting part. However, because the member S and part E do not have stable shapes and means for locating the member S in place on the part E, the seal member may not be located precisely in place when the assembly is completed, so that the seal is not completely liquid-tight.
It is an object of the present invention to provide a construction for mounting a pump on a small watercraft of the water jet propulsion type, wherein the pump can be mounted with a seal member in a liquid-tight connection easily, quickly and reliably without skill, and wherein the seal member can be used again when the pump is overhauled.